As is known, systems have been proposed in the past to convert one type of energy into another type by using various thermodynamic cycles, such as the Otto, Rankine and Brayton cycles. Most of these systems employ reciprocating pistons; although some, such as those shown in Dutch Pat. No. 65,164 and German Pat. No. 842,845, employ one or more pistons which are forced to travel in one direction in a continuous closed-loop by the expansion of a gaseous medium in one region of the closed loop. In the closed-loop systems of the prior art, each piston is coupled to a mechanical element which moves with it, the kinetic energy of the moving piston being converted directly into mechanical energy. These systems, however, require complicated mechanisms for coupling the piston or pistons to an associated mechanical element.
In U.S. Pat. No. 3,859,789, a method and apparatus are disclosed for converting one form of energy into another form of energy through the use of a single continuous, closed-loop passageway containing a plurality of freely-movable, mechanically-unrestrained bodies which travel around the passageway in one direction only. Acceleration of the bodies is effected by means of an expanding fluid medium supplied externally to the closed-loop passageway or by means of internal combustion. The kinetic energy of the bodies is extracted by a variety of methods including causing the propelled bodies, when formed from magnetically-permeable material, to pass through an electromagnetic field to convert some of the kinetic energy into electrical energy. Kinetic energy is also extracted by compressing the fluid between the bodies to provide energy in the form of compressed fluid. When the expansion of a gas is used to propel the bodies in this type of energy converter, the bodies pass through a region where the gas between them is compressed preparatory to a succeeding cycle of operation. In all such prior art systems of this type, the closed-loop passageway itself remains stationary.